Mining machine having extensible and retractable boring arm



y 4,1960 A. B. JACKSON 2,937, 59

MINING MACHINE HAVING EXTENSIBLEI AND RETRACTABLE BORING ARM Filed June 6, 1958 2 Sheets-Sheet 1 May 24 1960* A. B. JACKSON 2,937,859

MINING MACHINE HAVING EXTENSIBLE AND RETRACTABLE BORING ARM Filed June 6, 1958 2 Sheets-Sheet 2 2 H64. FIG.5. 25

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Un t W Pawn O MINING MACHINE HAVING EXTENSIBLE AND RETRACTABLE BORING ARM Alltoii B. Jackson, Nashville, Ill., assignor to National Mine Service Company, Pittsburgh, Pa., a corporation of West Virginia Filed June 6, 1958, set. No. 740,487

5 Claims; c1. 262-46 The invention relates to a mining machine in which cutting tools are carried on an arm rotating about an axis normal to the face being cut, the arm being extensible and retractable transversely of the of rotation.

The objects of the invention are to extend and retract the arm by a fluid pressure device but to hold the arm in extended position by a positive support independent of the fluid pressure device; to facilitate 'the shifting of the arm parts relative to each other by rendering the action of the holding support automatic when the fluid pressure device is actuated toextend or retreat thearm; and to embody the extending and retracting and holding mechanism within-the arm and thereby protect the mechanism from injury and from being made inoperative because of exposure to debris from the cutting operation.

In the accompanying drawings illustrating a selected embodiment of the invention:

Figure 1 is a side view of the forward end of a continuous mining machine showing a pair of cutter rotor arms in vertical extended position.

Figure 2 is a front elevation of the machine shown in Figure 1 and showing another pair of cutter rotorarms in horizontal extended position.

Figure 3 is a transverse section on line 33 of Figure 2, drawn to an enlarged scale, but showing one pair of arms in retracted position.

Figure 4 is a detail front view of the parts shown in Figure 3 with a portion sectioned approximately on line 4-4 of Figure 3 but showing the means for positively holding the arms in extended position.

Figure Sis a similar detail view of one of the arms of Figure 4 but showing the initial movement of the operating and holding mechanism when the arm is to be retracted.

Figure dis a detail view similar to Figure 5 but shows the position of the operating and holding mechanism at the end of the retracting operation.

Figure 7 is a detail view similar to Figures 5 and 6 but showing the operating and holding mechanism at the beginning of an extending operation.

Figure 8 is a detail transverse section through the arm on line 8-8 of Figure 7.

Figure 9 is a similar section on line 99 of Figure 7.

The mining machine embodying the invention is of a type well known in the art and includes a frame indicated at 1 mounted on an endless track 3 and journaling twin rotor shafts 5 each of which mounts a double cutter arm 7, 9. Arms 7 and 9 are substantially duplicates of each other, and only one of them will be described. It is to be understood that the invention may be utilized in a single arm.

The arm consist of two telescoping members of hollow box cross section, an inner or base member 11 and an outer or cutter carrying member 13. The members fit one within the other so as to telescope and be shifted from a retracted position (as shown in Figure 3) to an extended position (as shown in Figures 1, 2, 4 and 5). Extension and retraction of the arm members are effected by a fluid "Ice pressure device'corresponding to hydraulic jacks generally used in mining machines and including a cylinder 15 pivoted at'its inner end to base member 11 by a.pin 17 extending transversely of the cylinder axis. A piston 19 in the cylinder is providedwith an elongated rod 21. A strut-like part 23 in the form of a bell crank is pivoted at its knee by a trunnion 25 seated in opposite walls of cutter carrier member 13. The swinging end of the short horizontal arm of part 23 is pivoted at 27 to the outer end of piston rod 21. Pin 17 is seated in opposing walls 11a of the base'member and trunnion 25 is seated in the corresponding walls 13a of the cutter carrier member. Each walll 11a is provided with a guide 30 cooperating with the transverse wall 11b to form a slot 29 open at the outer end of the member and there offset transversely of the member and cylinder-axis to form a shoulder 37. The swinging end of the long leg of part 23 is provided with a cross bar 31, the ends of which are slidable in slots 29.

Fluid under pressure is admitted to cylinder 15 at opposite sides of piston 19, selectively, from a hydraulic pump or air compressor (not shown), mounted on the machine, through conduits 33, 35 controlled by suitable manually operated valves (not shown). When fluid is supplied through conduit 35', the piston first shifts bell crank 23 from the position shown in Figure 6 to the position shown in Figure7, when cross bar 31 contacts the right hand faces of slots 29. Further movement of the piston is transmitted through the bell crank and trunnion 25 to the cutter mounting member 13 of the arm. The latter is projected into operating position (Figure 4). As cross bar 31 reaches the outer end of arm base member 11 it moves to the right over shoulder 37. The fluid supply valve may now be closed and the bell crank will serve as a rigid thrust transmitting part positively holding the telescoping arm members in extended relation.

When the arm is to be retracted, as may be required when the machine is to he moved out of the cut, the operator admits fluid to conduit 33 and piston 19 is moved inwardly of cylinder 15. The first effect of this movement is to swing the bell crank on trunnion 25 from the position shown in Figure 4 to the position shown in Figure 5. This swinging movement shifts cross bar 31 off of shoulder 37, whereupon the cutter mounting member may move toward the arm hub until the arm members are again in the position shown in Figures 6 and 3. It will be apparent that the movement ofnbell crank 23 into and out of thrust transmitting position is automatically at the end of an arm extending operation and at the beginning of an arm re- 7 tracting operation respectively.

With this construction, the impacts on the outer ends of the rotor arm are carried direct by the bell crank and the shoulder on the arm, and not by the fluid pressure device, and this avoids the necessity of maintaining fluid pressure in the device during operation, and avoids excessive pressure which would be likely to injure the device, rupture the hose or require a pressure relief valve.

Preferably the bell crank comprises a pair of spaced units, as best indicated in Figures 8 and 9. While the cutter arm as shown comprises a pair of telescoping members at each side of the hub, it is within the scope of the invention to have the telescoping members at one side of the hub only.

Other variations in the details of the construction may be made without departing from thespirit of the invention and exclusive use of those modifications coming within the scope of the claims is contemplated. a

I claim:

1. A mining machine rotary cutter arm comprising an arm base member and a cutter carrier member, said members being elongated and telescopically assembled to move along a common axis normal to the axis of rotation of the arm to extended and retracted positions, a fluid pressure operating device for extendingland retracting the members comprising a cylinder within and secured to one of said members and provided with a piston having a piston rod projecting from the cylinder toward the other member, means for selectively admitting fluid under pressure to opposite sides of said piston, 21 rigid thrust-transmitting part pivotally connected to the outer end of said piston -and having a pivot mounting on the latter-mentioned member at one side of said common axis and including a portion spaced from said pivot mounting and movable about said pivot mounting transversely of said common axis, by the projection of said piston, to a position in which said portion positively engages the cylindersecuring member to hold said member extended, said thrust-transmitting part portion being positively moved about said pivot mounting from said engaging position to a disengaging position when the piston is retracted.

2. A mining machine cutter arm according to claim 1 in which the thrust-transmitting part is elongated in the direction of said common axis and is pivoted at its outer end to the cutter carrier member and its inner end is swingable selectively over and away from an outwardly facing shoulder on the base member.

3. A mining machine cutter arm according to claim 1 in which the piston rod projects beyond the outer end of the cylinder and the thrust-transmitting part comprises a bell crank lever pivoted at its knee to the cutter carrier member with one leg of the lever extending transversely of said common axis and being pivoted to the outer end of said piston rod and the other lever leg extending substantially parallel to said common axis and being movable transversely thereof to and from a position opposing an 4 outwardly facing shoulder on the rotor cutter arm base member.

4. A mining machine rotor cutter arm according to claim 1 in which one side wall of the cylinder mounting member has an elongated guide face paralleling the common axis of said members and a shoulder offset inwardly from said face at the outer end of the wall, and the thrust-transmitting part comprises a bell crank pivoted at its knee on the cutter carrier member at a point spaced from said common axis and having a short leg pivoted to the end of the piston rod and having a long leg with a transverse lug at its swinging end slidably received in said guide face and movable over said shoulder when the lug reaches the outer end of said guide face.

5. A mining machine rotary extensible cutter arm according to claim 1 in which the cylinder unit is secured at its inner end to the inner end portion of the base member and the thrust transmitting part is pivotally secured to the outer end portion of the cutter carrier member at a point on said part spaced from the axis of the piston.

References Cited in the file of this patent UNITED STATES PATENTS 804,510 Vaughan Nov. 14, 1905 1,772,892 Green Aug. 12, 1930 1,824,866 Bristol Sept. 29, 1931 1,852,453 'Forman Apr. 5, 1932 2,204,279 Meyer June 11, 1940 2,333,274 Scannell Nov. 2, 1943 2,711,887 Robbins et al June 28, 1955 2,734,731 Cartlidge et a1 Feb. 14, 1956 2,890,033 Silks June 9, 1959 

